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(No Model.)

0. J. VAN DEPOELE.

SAFETY DEVICE FOR ELEGTRIG MOTORS.

No. 394,417. Patented Dec. 11, 1888.

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UNITED STATES PATENT Orince.

CHARLES J. "AN DEPOELE, OF CHICAGO, ILLINOIS.

SAFETY DEVICE FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 394,417, dated December 11, 1888.

Application filed June 6, 1888. Serial No. 276,255. (No model.)

To aZZ whom, it may concern:

Be it known that 1, CHARLES J. VAN DE- POELE, a citizen of the United States, residing at Chicago, in the county of Cook, State of Illinois, have invented certain new and useful Improvements in Safety Strips and Signals for Electric Motors, of which the following is a description.

This invention comprises a device for pro-' which might be otherwise attended by serious results.

The invention consists in interposing between the connnutator and field-magnet connections and the main terminals of the machine a piece or section of insulating material of less insulating capacitytha t is, more easily destroyed or punctured than the insulation upon the wires with which the various parts of the motor are wound. It follows from this construction that on the presence of a dangerous, extra, or other current it will necessarily find outlet through the safety device, destroying the same, but thereby protecting or saving the rest of the machine harmless.

An illuminating device is placed in circuit with the safety device, so that when the safety-strip has been destroyed the illuminating device will be brought into action giving notice to the attendant to replace the safetystrip.

The construction and operation of my safety device will be hereinafter fully set forth, and shown in the accompanying drawings, and also referred to in the appended claims.

Figure l is a theoretical diagram showing a motor and safety device embodying my invention. Fig 2 is a detail view of a desirable form of the apparatus arranged for use.

Similar letters denote like parts throughout.

As shown in the drawings, A represents the core of the field-magnet ot' a mot or, of which a and B are the ei'iergizing-coils. From the field-magnet the current passes by conductor 1 to the positive comnmtattw-brush C, thence to the commutator D and armature, issuing by brush E, and passing ihence to line by conductor F is a rheostatic device for controlling the admission of current to the coils of the fieldmagnets, and said device receives the main current through conductor G represents a coil or strip of wire, preferablyof platinum orothermetal or material capable of being raised to a visible heat without destruction. The conductor G is connected with one of the field-magnet conductors by conductor t, and its other extremity leads by conductor 5 to a metallic block or strip, H, which abuts against a second metallic block or strip, I, between which is placed a strip of paper or other suitable insulating material, '2', which is connected to the line-wire by attachment to main conductor 2. A small piece of iron or lead wire may, however, be substituted for the blocks H I and insulating-strip 'i.

henever in the operation of the motor an extra currentexists, no matter from what cause or how produced, the resistance of the strip i being somewhat less than that of the re sistance of the other conductors of the sys' tem, said current will puncture or completely destroy the said strip 2', (or burn or melt the wire which may be substituted therefor) when the safety-strip will be closed, and the current flowing through the wire G will raise the same to redness or incandescencc, so that it will be visible to the attendant, who will then replace theinsulation z, and thus restore the function of the safety-circuit. IVhen a piece of wire is used instead of the paper strip 2, a visual signal will be produced by its destruction, but only for an instant, for the safety-circuit will then be broken and remain so until restored by a new safety-wire.

In a separate application filed simultaneously herewith I have shown, described, and claimed a safety device adapted to temporarily and automatically increase the resistance of the circuit in which it is placed, and thereby prevent injurious shortcircuiting. The device refer *ed to is shown at K in Fig.

2 hereof, in connection with which is shown, as a desirable form of the invention just described, an incandescent lamp, L, taking the place of the wire G, so that on the destruction of the strip iand the closing of the safetycii'cuit through conductors 4, 5, and 6 the lamp L will be set burning and remain so until the safety-strip t' is replaced.

The device shown at K in Fig. 2 is herein referred to as an automatic resistance also comprising a light-giving device, and is more par ticularly described and specifically claimed in my said other application, No. 276,254.

The above-mentioned apparatus is adapted to be included in the main circuit of the machine to be protected, and when so included will operate under excess of current to form an arc of greater or less length and corresponding resistance in proportion to the excess of supply-current.

The particular construction and arrange-- ment of the automatic resistance and lightgiving device being set forth in my said other application is not herein pointed out, said device being only claimed in this application in combination with the safety device spanning the terminals of the machine to be protected.

In describing my invention I have explained its application and shown it for purposes of illustration only in connection with a particular form of motor. It will be understood, however, that it is not my intention to limit the same to any special structure, machine, or system. The invention is for the purpose of protecting electric machines generally from the damage to their insulation caused by the extra currents observable whenever the main circuit is broken, said currents being induced in the coils by the sudden discharge of the magnetism of the machine.

The extra currents referred to being of very short duration a device such as hereinbefore as set forth.

Having described my invention, what I claim, and desire to secure by Letters Patent, is

1. The combination, with an electric motor or other machine, of a circuit spanning the terminals thereof, a signaling device in said circuit, and a pair of terminals also in said circuit and normally separated by insulation of less resisting power than the insulation of the conductors of the machine, substantially as described.

2. A safety-circuit for motors, comprising a circuit spanning the terminals thereof and including a visual signal and a pair of terminals separated by insulation of less resistance than the other parts of the circuit of the machine, whereby when said resistance is destroyed by the presence of an abnormal current pressure or potential the visual signal will give notice of the fact, substantially as described.

3. A safetyapparatus for electric motors and generators, comprising a transparent box or casing containing an electric light-giving device included in a normally-open safety-circuit spanning the terminals of the machine to be protected, and an adjustable automatic re sistance also comprising a light-giving device, said automatic resistance being placed in the main supply-circuit of the machine to be protected and adapted to limit the amount of current flowing therethrough, substantially as described.

In testimony whereof 1- hereto affix my signature in presence of two witnesses.

CHARLES J. VAN DEPOELE.

\Vitnesses:

W. A. STILEs, JOHN EASON. 

